1. Field of the Invention
The present invention relates to a vibration type actuator generating vibration in a vibrator to cause a driven body to make a relative movement, a vibrator of a vibration type actuator, and a vibrator manufacturing method.
2. Description of the Related Art
In a vibration type actuator, a contact portion to be brought into press contact is endowed with resiliency, whereby a smooth contact can be realized, and a satisfactory performance can be obtained. As illustrated in FIG. 11, in a linear vibration type actuator discussed in Japanese Patent Application Laid-Open No. 2008-125147, a vibrator 110 is provided with protrusions 119 each equipped with a contact portion 113 exhibiting resiliency.
The protrusion 119 is composed of the contact portion 113 having a contact surface 114 to be brought into contact with a driven body (not illustrated), a fixation portion 117, and a connection portion 116 connecting the contact portion 113 and the fixation portion 117, and the fixation portion 117 is fixed to an elastic member 112 by laser welding or the like. In order that the contact portion 113 may exhibit resiliency, the elastic member 112 is provided with a groove portion 118 of a sufficient depth. The elastic member 112 is provided on a piezoelectric member 115.
The provision of a vibrator with a contact portion with resiliency is not limited to a linear vibration type actuator. As discussed in Japanese Patent Application Laid-Open No. 2006-311790, there exists a rotary vibration type actuator for generating a progressive wave in an elastic member whose vibrator has at the distal end of a protrusion thereof a resilient contact portion joined thereto.
However, the conventional constructions described above have the following problems. In the linear vibration type actuator discussed in Japanese Patent Application Laid-Open No. 2008-125147, to increase the moving speed of the driven body, it is necessary to heighten the contact surfaces 114 of the vibrator 110, which are brought into contact with the driven body, to thereby enlarge the vibration amplitude in the feeding direction (the X-direction).
However, heightening the contact surface 114 results in a reduction in the rigidity in the X-direction of the connection portions 116, so that, although high vibration speed can be attained, it is difficult to transmit drive force efficiently to the driven body. Further, since the resonance frequency of the vibration mode in which the protrusions 119 vibrate is reduced, unnecessary vibration is likely to be generated, so that, in some cases, it is difficult to obtain a satisfactory actuator performance.
Also regarding the rotary vibration type actuator as discussed in Japanese Patent Application Laid-Open No. 2006-311790, heightening the contact surfaces results in a reduction of the rigidity in the peripheral and radial directions, and unnecessary vibration may easily occur.